Mobile devices are rapidly becoming commodity items. Increasingly, successful manufacturers compete not only on price, but differentiate their products via unique interfaces, device packages or other features. As consumer tastes shift, short product cycles and rapidity-to-market are at a premium.
Furthermore, mobile devices must continue to evolve, supporting a variety of activities inherent in their emerging status as primary communication devices. These devices, which include mobile phones as well as PDAs like BlackBerry™ and notebook computers equipped with mobile connectivity cards, must handle relatively high bandwidth communications such as IMAP email, graphical web browsing, and the like, not to mention bandwidth intensive applications such as video streaming or IP telephony. Because the majority of all mobile communications rely on device antennae, requirements placed on mobile device antennae are ever-increasing.
Antennae are key contributors to the quality of devices' communications capabilities. Further, they must conform to size, shape and volume constraints as mobile devices are produced with form factors of ever-decreasing size. In addition, they must meet stringent requirements for electronic interference, safety, and other regulated characteristics.
Antennae must also be easy and cheap to manufacture, as well as cheap and easy to re-design. To shorten the mobile device products cycle, the lead times required for all hardware component design, manufacture, and re-design must decrease. However, quality should not fall below consumer tolerances.
Currently, even cheaply produced reliable antennae require long hardware design and manufacture lead times. For example, planar antennae provide a popular solution to the antenna problem. Though these antennae have a high initial cost—in both time and in money—they have a relatively low marginal cost to manufacture. They are lightweight and low volume to fit ever-shrinking device packaging.
There are a variety of constructions known for planar antennae, including stamped sheet metal and metal layered on printed circuit board (PCB). However, all of these methods require lead-time to set up custom tooling or etch masks to produce every new planar antenna design. Thus, for each modification to the antenna design, tool and etch mask changes require days or weeks of delay, lengthening the product re-design cycle.
Furthermore, planar antenna designs are sensitive to material selection, and design changes may necessitate material shifts. This requires manufacturers to maintain a diverse array of materials on hand, and pay the accompanying carrying costs, even during re-design lead-time delays.
In addition, these planar designs are typically produced as separate components from the main circuitry of the device, and thus require specialized adaptation for connection to the device electrical system. Often these connections are made galvanically and the antenna held in place via spring forces. For example, as shown in FIG. 1C, the planar antenna section 200″ includes a body 201″ coupled with a separate spring clip 210″. The spring clip 210″ is deformed upon mounting to the device body, producing a force directed along the arrow. This force holds a contact in place, providing electrical connection between the antenna 200″ and the main circuitry of the device (not shown). The need to include and engineer for separate forcing clips adds cost and complexity to the antenna design.
Another type of antenna design requires high initial costs, high manufacturing costs, exotic materials, and separate connector components. These sintered metal antennae are currently used in high-end devices optimized for performance.
For example, a two-part sintered antenna system is shown in FIGS. 1A and 1B. The antenna assembly 200 of the two-part system is shown in FIG. 1A. The antenna assembly 200 includes the radiator 220, which is mounted on a support chassis 210.
The radiator 220 includes a folded portion 222 and a stem 224. The stem 224 is adapted for interface with an antenna coupling spring (210′ of FIG. 1B). The support chassis 210 includes an upstanding portion 212 that is adapted to interface with and support the radiator 220. The radiator 220 is mounted to the upstanding portion 212 of the support chassis 210 so that the stem 224 is aligned along a planar surface of the support chassis 210.
The shape of the radiator 220 is determined via a unique molding-and-sintering process. A specific mold is produced in the shape desired, metal powder is inserted into the mold along with a binder, then the resulting shape is sintered to produce a shaped piece of metal. To improve conductivity, the shape is then surface coated with a highly conductive material, such as gold.
The main circuit assembly 200′ of a two-part sintered antenna system is shown in FIG. 1B. The main circuit assembly 200′ includes the board 201′, preferably a printed circuit board (PCB). Various internal components and couplings of the main circuit assembly 200′ are mounted to the board 201′.
As illustrated, the main circuit assembly 200′ includes the antenna processor 220′ and the control circuit 230′. The antenna processor 220′ is coupled to the control circuit 230′ via the primary coupling 204′ and the secondary coupling 203′. In addition, both the antenna processor 220′ and the control circuit 230′ components communicate with interfaces and couplings of the mobile device (not shown) external to the main circuit assembly 200′. The components are also coupled with the antenna assembly 200 of the two-part system.
The antenna processor 220′ is connected to an antenna contact interface 210′. The connection is made via the antenna input coupling 202′. The antenna contact interface 210′ of the main circuit assembly 200′ is adapted to interface with the stem 224 of the radiator 220 and provide sufficient contact force at the interface to facilitate both electrical communications and some measure of physical stability.
The antenna contact interface 210′ includes the contact spring fins 212′, which are positioned and configured to interface with the stem 224 of the radiator 220. The spring fins 212′ are constructed of a conductive, resilient material. Coupling the stem 224 to the spring fins 212′ causes the fins 212′ to deform away from each other, forming a stress that forces the fins 212′ against the surface of the stem 224. This forcing produces a contact force sufficient to facilitate electrical communications and retention of the stem 224 within the contact interface 210′.
Thus, the construction of an antenna system around a sintered-metal radiator requires not only a specialized mold and an exotic coating, but also separate elements to provide coupling force between the radiator and the device circuitry. The forming methods require lead-time to set up custom tooling and molds to produce every new or revised antenna design. Thus, for each modification to the antenna design, tool and mold changes require days or weeks of delay, lengthening the product re-design cycle. In addition, the need to include and engineer for separate forcing springs adds cost and complexity to the antenna design.
What is needed is a method or design of antenna that maintains quality and maintains or lowers incremental costs while shortening lead-time for redesign, implementation and manufacture.
What is needed is a method or design of antenna that permits a variety of antenna designs, specifications and capabilities to be produced via a single machine and/or type of material, dramatically reducing the stock value of raw materials needed to avoid manufacturing slow-downs.
A method that would permit a design change to enter production within a few hours, and with substantially the same raw-materials input, would dramatically lower the cost of manufacture for mobile device antennae.
What is also needed is a method or design of antenna that integrates contact spring functionality into the antenna radiator itself.